G'day all. I wrote:
- Intuitionistic logic systems. - The "truth values" of an arbitrary topos (i.e. the points of the subobject classifier).
Sorry, I misread the question. These are _not_ instances of Boolean (or at least the latter isn't an instance in general). Cheers, Andrew Bromage _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
